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The Book of Vaadin examples? http://demo.vaadin.com/book-examples-vaadin7/book/
But to the best of my knowledge, we don't re-visit older examples only to use the latest Java7 or Java8 features. So once some code is written and published, it will stay until it needs more features or will no longer run with a recent web environment (JVM, Tomcat, Jetty, Browser...).